Probiotic encapsulation: Body armour for the bugs

Most foods containing probiotic bacteria are found in the refrigerated section of supermarkets, as the bacteria are destroyed by heat and other processing conditions.

This has given the dairy sector, already used to handling live bacteria for the manufacture of yoghurt, a major advantage in probiotic foods - probiotic drinking yoghurts are currently the fastest growing dairy product in Europe.

But increasing research has focused on expanding protecting probiotics during processing and expanding the food categories currently available to prebiotic fibres.

Probiotics are bacteria found in the gut that are understood to have health benefits.

Prebiotics are ingredients that stimulate growth of probiotics in the gut.

Synbiotics are a combination of the two. Companies such as Korea-based Cell Biotech have been exploring was to coat and encapsulate the gut-friendly bacteria.

Its technology involves coating the probiotic cultures to increase stability in processing and formulations and to improve survivability through inhospitable gastric juices and bile salts, until they reach the gut.

The first layer of coating is soy peptides, while the second phase uses cellulose and gum to yield the final DuoLac product.

Combining these coatings, the probiotic is said to be stabilised during ingestion and have a longer shelf life than non-coated lactic acid bacteria, as well as being protected against oxygen, acid, moisture and high temperatures.

Other approaches are also being explored, with scientists looking at improving probiotic viability by using prebiotic fibres, or whey protein gel particles.

Encapsulation of probiotics in whey protein gel particles could offer protection during processing and storage, as well as extending the food applications of the bacteria to biscuits, vegetable and frozen cranberry juice.

Researcher Claude Champagne from the Food Research and Development Center Agriculture and Agri-food Canada told NutraIngredients.com recently: "We were the first to apply the [whey gelation] technique to probiotics and it has subsequently been picked up."

Champagne added that the protein-based technique could provide an alternative to microencapsulation (ME) with alginate-type gels or spray-coating with fats, the two most widely-used probiotic encapsulation methods.

"It can be expected that the protein matrix would have different cell release properties than the other ME methods (polymer or fat based)," said Champagne.

"Thus, applications can extend to other foods for protection during processing as well as stability during storage but also in nutraceuticals for protection and cell release in the GI tract.

Industrially, Lallemand has developed a way to use coated probiotics in chocolate, which could be used as a filling in biscuits, nutrition bars, or chocolate drops for addition to breakfast cereals.

Crucially, the bacteria need to be added after cooking as they do not survive heat.

Moreover, the chocolate vector is said to be ideal since chocolate processing does not require much processing.

Chocolate has also been a focus for DSM Food Specialities; a bar called Attune containing its Lafti probiotic brand recently launched in the US, and contains five times the amount of probiotics as yoghurt.

A final potential breakthrough in probiotic encapsulation was reported recently by scientists from the Technical Research Centre of Finland (VTT) who investigated the capabilities of various prebiotic fibres to protect the stability and viability of probiotic Lactobacillus rhamnosus strains during freeze-drying, storage in freeze-dried form and after formulation into apple juice and chocolate-coated breakfast cereals.

Speaking to NutraIngredients.com, lead author Maria Saarela said that by choosing the right combination of pre- and probiotic the stability of the latter could be enhanced for a specific application.

"Perhaps the main finding in this study was that different fibres can be used in different applications: polydextrose and dextrin were good freeze-drying carriers and for dry applications whereas oat rich in beta-glucan was a good carrier for fresh cells in apple juice," she said.

In the International Journal of Food Microbiology , Saarela wrote: "The present study indicated that some fibre preparations have the potential in technological applications in protecting probiotic viability and stability during processing and storage in food matrices."

References: Journal of Food Science Volume 72, Number 1, Pages M31-M37; doi: 10.1111/j.1750-3841.2006.00222.x "Survival in food systems of Lactobacillus rhamnosus R011 microentrapped in whey protein gel particles" Authors: A. Ainsley Reid, C.P. Champagne, N. Gardner, P. Fustier, J.C. Vuillemard International Journal of Food Microbiology November 2006, Volume 112, Issue 2, Pages 171-178 "Fibres as carriers for Lactobacillus rhamnosus during freeze-drying and storage in apple juice and chocolate-coated breakfast cereals" Authors: M. Saarela, I. Virkajärvi, L. Nohynek, A. Vaari and J. Mättö